OTN (Optical Transport Network), which are recommended by the ITU (International Telecommunication Union), have been known as one of the standards for transmitting signals in an optical network (e.g., core network). In OTN, client data is stored in OTU (Optical channel Transport Unit) frames and is transmitted.
As a related art, there is a transmission apparatus that transmits an Ethernet (Registered Trademark) signal by using plural OTU2 signals. Note that Japanese Laid-Open Patent Application Publication No. 2010-148104 is known as related art.
In recent years, further increases in speed and capacity have been needed in optical networks. For that reason, in OTU, a configuration that parallelizes signals before processing and transmitting the signals has been put into practical use.
However, in a transmission system that parallelizes signals before processing and transmitting them, the time to process frames may become longer when an attempt is made to increase the transmission rate. For example, a time needed to establish synchronization may become longer in the transmission apparatus at the receiver end.